Stabilization of the (π-Indenyl)–Lead Bond: The First Structurally Authenticated Bis(η5-indenyl) Complex of a Post-Transition Element, [Pb{1,3-(SiMe3)2C9H5}2]

✍ Scribed by Jason S. Overby; Prof. Timothy P. Hanusa; Dr. Paul D. Boyle

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 301 KB
• Volume: 36
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.199723781

✦ Synopsis

addition of hexacdrbonylchromium (0.28 g, 1.25 mmol) the resulting suspension was allowed to warm to room temperature over a period of 4 h. The solvent was removed in vacuo, and the residue was dissolved in dichloromethane (50 mL). After addition of [Me,O][BF,] (0.18 g, 1.25 mmol) at O T , the mixture was stirred for 1 h. Yield: 0.45 g(0.52 mmol, 51 Yo). I3C NMR (100 MHz, CDCI,): 6 = 338.0(C=Cr), 225.2 (trans-CO), 216.5 (cis-CO), 156.1 (C-l), 97.0 (C-2), 81.8 (C-3), 69.1 (C-4), 66.8 (C-5), 66.4 (OCH,), 61.2 (C-6), 18.2-18.0 (SiCH(CH,),), 12.5-12.0 (SiCH(CH,J,). 2b (42%) and 2c (58%) were obtained similarly. 5: nBuLi (0.7 mL, 1.12 mmol) was added to a solution of 11 (0.92 g, 1.02 mmol) in THF (5 mL) at -78°C. The solution was stirred at this temperature for 1 h and then added to a suspension of 3 (0.51 g, 1.12 mmol) in THF precooled to -78 "C or, alternatively, to a solution of 4 (18.6mL, 1.12mmo1, 0 . 0 6 ~ in THF). The solution was stirred for 14 h and allowed to warm to room temperature. Yield. 0.36 g (0 57 mmol, 56%) from the reaction with 3; 0 26 g (0.41 mmol, 40%) from 4. I3C NMR (62.5 MHz, CDCI,): 6 = 325.7 (C-l), 225.7 (trans-CO), 216.5 (cis-CO), 136 0 (C-2), 125.5 (C-3), 86.3 (C-4), 62.1 (C-5), 61.7 (C-6), 18.3-18.1 (SiCH(CH,),), 12.7-12.0 (SiCH(CH,),). HR-MS: Calcd. for C,,H,,CrO,Si,: 632.2293; found: 632.2284.

6: A solution of 2a (0.32 g, 0.32 mmol) and 3-hexyne (0.5 mL, 4.0 mmol) in THF (4 mL) was degassed (three cycles "pump, freeze, thaw") and then warmed to 50 "C for 6 h. Work-up by column chromatography afforded 6 (0.14 g, 0.16 mmol, 40%) and 7 (0.09 g, 0.11 mmol, 30%). "C NMR (100 MHz, CDCI,): 6 = 234.4 (Cr-(CO),), 134.1, 132.7, 118.6, 112.0, 90.14, 83.4, 67.7, 65.6, 64.8, OCH,), 21.8 (ArCH,CH,), l9.6(ArCH,CH3),),), 16.0 (ArCH,CH,), 14.8 (ArCH,CH,), 13.0-11.8 (SiCH(CH,),).

8: A 10 s flow of ammonia was condensed at -78°C into a solution of 5 (0.29 g, 0 46 mmol) in dichloromethane (20 mL). The solution was stirred at this temperature for 1 min. Work-up by column chromatography afforded 8 (0.24 g, 0.37 mmol, 80%). "C NMR (100 MHz, CDCI,): 6 = 276.6 (C=Cr), 223 0 (rrans-CO), 217.4 (SiCH(CH,),), 12.5, 11.8 (SiCH(CH,),). HR-MS: Calcd. for C,,H,,NCrO,Si, (M' -5CO): 509.2825; found: 509.2819. 9: A solution of ethoxyethyne (0.59 mmol) in petroleum ether (1 mL, 40/60) was added to 5 (0.31 g, 0.49 mmol) in petroleum ether (20 mL, 40/60) at -20 "C. The solution was stirred for 24 h at room temperature, (0.26g, 0.37 mmol, 75%). I3C NMR (100 MHz, C,D,): d = 322.9 (C=Cr), 224.6 (trans-CO), 217.8 (cis-CO), 148.6 (C-l), 143.5, 125.0, 121.4 (alkene-C), 81.6 (C-4). 76.2 (OCH,CH,) , 63.23 ),), 14.9 (OCH,CH,), 12.8, 12.3 (SiCH(CH,),). HR-MS: Calcd. for C,,H,,O,Si,Cr ( M + -5CO): 562.2933; found: 562.2949. Ammonolysis of 9 was carried out similarly to that of 5.